What is hormone?

 Hormone

harmony is a chemical substance that is secreted into the internal body fluid by endocrine glands and exerts a physiological control effect on other cells of the body. 

Biomedical importance

   a. Essential for body function : e. g.

      ☞ Metabolism : Insulin, Glucagon, thyroid, cortisol.

       ☞ Growth : Growth hormone 

       ☞ Reproduction : testosterone, oestrogen.

      ☞ combating emergency : Adrenalin and noradrenalin.

  b. There are some disease directly related to hormone, cushing syndrome.

  c. many drugs are prepared from hormones. 

Properties of hormones 

 ➤ synthesize by endocrine gland.

 ➤ Belongs to different types of chemical structure. 

 ➤ Not initiate reactions in cells.

 ➤ Not secreted in uniform rate.

 ➤ easily soluble and diffusible.

 ➤ Exhibit a high degree of specificity.

 ➤ Works within a limit.

 ➤ Exert multiple action. 

Mechanism of action of hormone :

Hormone acts by this mechanism-

Binding with specific receptor ( hormone receptor is type of plasma protein that present is target cell membrane) 

   Formation of hormone receptor complex

stimulation of product SMP (second messenger mechanism) 

stimulation of genetic materials by SMP for action. 

Target tissue:

The particular tissue of which a specific hormone acts is called target tissue of that hormone. it may be general tissue cells or other endocrine cells.

Hormone receptor ;

these are large protein molecules located in the prisma membrane, cytoplasm and nucleus of the cells. hormones initiate their biologie effects by binding to specific receptors. 

 ➤steroid and thyroid hormones interact with intracellular receptors. The receptors for steroid hormones and thyroid hormones are found in the cytoplasm and in tha nucleus, respectively.

 ➤ Polypeptide, protein, hirmones bind to receptors located in or the surface of thw cell membrane.